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30 The PCB Design Magazine • September 2014 ments includes an expanded definition of the stack-up. This enhancement exemplifies the innovation that the Consortium collaboration has achieved. IPC-2581 rev B Stack-up Exchange The idea behind enhancing the stack-up definition within IPC-2581 was simple, yet brilliant. As we all know, for many designs with high-speed requirements, design bureaus send their requirements to their fabrication/ manufacturing partner, such as achieving 75 ohms on a certain layer. The fabricator sends a suggested layer stack-up for review and ap - proval. This collaboration happens today with spreadsheets, Microsoft PowerPoint, Microsoft Word documents and a few phone calls. The suggested stack-up is entered into the PCB layout tools manually (painfully). Any discon- nect between the fabricator and the design bureau is not discovered until after the design is completed. Last-minute changes to a com- pleted design can be very time-consuming and painful. With IPC-2581 rev B, the design bureau and fabricator can exchange the proposed stack-up electronically, and since it can be consumed by the PCB design tools, it saves a lot of time enter- ing the data into the PCB CAD tools. More im- portantly, there is little chance of introducing errors in the process. The stack-up definition has the capabilities to describe a stack-up in a designer's perspective or from a manufacturer's perspective. A design view may show a basic view of a stack-up, and a manufacturer's view may display the multiple materials to make up a dielectric or core layer build up. BOM references for the stack-up materials are also built into the IPC-2581 data. Adoption The consortium launched with 11 founding members and has grown steadily over the past two years with more than 60 members today. Consortium members have built boards using IPC-2581 through several manufacturing com- panies. Figure 8 depicts the latest support status for IPC-2581, which is updated on the consortium website on a regular basis. feature IPC-2581 ADOPTION UPDATE continues Figure 5: Image of PCB successfully built by vellux.